Back in 1996 a rock was discovered in the Antarctic. This rock was important because, after analysis, it was discovered to be from Mars and it contained minute Martian bacteria in microfossil form.
Andy Smith

What are you blathering on about?
That's the basis of the background story for Take 2's game, Martian Gothic: Unification. Leap a few years into the future and a base has been established on Mars to research Martian bacterial life forms.

Oh I see. Doesn't sound very gothic so far.
I'm getting there. As is a game designer's wont, the base has been overrun and the player's got to go there and find out what's gone wrong.

Tsh! That was bound to happen, wasn't it?
Well, yes. Apparently a bacterial outbreak has occurred from a site below the base and killed everyone. This was no ordinary bacterium, though - it caused the human crew to fuse together in clumps of three if they got near to each other. Very messy.

Urgh! I'll be alright though because there's only one of me.
No you won't. You're actually controlling three people in the game - two blokes and a bird - and they have to keep themselves apart from each other or suffer the same fate.

Lawks. So I have three people to control?
Yup, and when you're controlling one of them, the other two are at the mercy of the ranks of Nondead that populate the base.